Image reading apparatus and image forming apparatus

1. Field of the Invention

The present invention relates to an image reading apparatus for reading image information of an original and is applied to an image forming apparatus, for example, such as an facsimile machine and the like.

2. Related Background Art

Heretofore in the past, this kind of the image reading apparatus has been available such as shown in FIG. 15 . As shown in FIG. 15 , an original pressing means 52 for pressing the original to a contact image sensor 51 as an image reading means was configured in such manner that it is contacted to the reading surface of the contact image sensor 51 .

The original pressing means 52 is configured by a white sheet 52 a as a reading reference (a color reference) and a white sheet metal 52 b . The white sheet 52 a is fixed with its upper portion screwed with a vis. The white sheet metal 52 b is fixed by hanging on an upper original guide above the inside of the apparatus at an original conveying direction downstream side.

Also, as shown enlarged in FIG. 16 , an emboss 52 c is disposed outside the original conveying direction area of a longitudinal both ends portion of the original pressing means 52 so that the original pressing means 52 is not adhered (or cohered) to the reading surface of the contact image sensor 51 .

Note that the original pressing means 52 at the time when the above described emboss 52 c is disposed is deprived of a function to press the original to the reading surface and given a function to guide the original at a reading location so as not to behave violently.

And, for example, at the time of the pre-scanning prior to the commencement of the image reading operation, the operation for detecting a reflective light volume from the reading reference 52 a and for deciding a white level (a color reference) to determine the output level (the contrast level) of the information read by the image sensor is activated.

However, in case of the above described prior art, the white sheet 52 a strongly contacts the reading surface of the reading location of the contact image sensor 51 and tends to adhere (or cohere) thereto owing to the fixing condition of the original pressing means 52 to the contact image sensor 51 , accuracy of each component thereof and the like. Then, the reflective state of light at the adhesive (or cohesive) surface is changed and the output of brightness which is the reading reference of the image is lowered, thereby causing the problem where the reading image becomes whitish. When this adhesion (or cohesion) arises at a longitudinal part, a malfunction occurs in which the portion where the output is lowered becomes white line (or streak) if seen from the whole reading image.

For this reason, in order to prevent the adhesion (or cohesion) of the original pressing means 52 , it was necessary to take measures such as the disposition of an emboss of high accuracy and the control of warping of the white metal sheet and the like.

The present invention is made to solve the above described problem of the prior art and its object is to prevent the adhesion between the color reference member and the reading surface with certainty and in a simple configuration and to provide an image reading apparatus and an image forming apparatus which can obtain a highly accurate reading image.

In order to achieve the above described object, the image reading apparatus of the present invention comprises:

conveying means for conveying an original; reading means for optically reading the information recorded in the conveyed original at a predetermined reading location; original pressing means for pressing the original to the above described reading means; a color reference member used as a color reference at the time when the above described information is read by the above described reading means; and in which the above described color reference member is disposed between the above described reading means and the above described original pressing means, and the pressing location of the original to the above described reading means by the above described original pressing means is disposed at a location within the original conveying area and other than the above described reading location.

Consequently, since with a simple and low-cost configuration without increasing the number of parts, the adhesion (or cohesion) between the color reference member and the reading surface by the original pressing member is prevented, and a definite color reference can always be obtained, the image reading apparatus does not develop any image defect in the reading image, thereby obtaining a highly accurate reading image.

FIG. 1 is a perspective view showing an original pressing means relative to the embodiments of the present invention;

FIGS. 2A , 2 B, 2 C and 2 D are three planes showing the original pressing means relative to the embodiments of the present invention;

FIG. 3 is a rough cross sectional view of an image reading portion relative to the embodiments of the present invention;

FIG. 4 is an enlarged view of a contact image sensor relative to the embodiments of the present invention;

FIG. 5 is a enlarged view showing the original pressing means and the contact image sensor relative to a second embodiment of the present Invention;

FIG. 6 is a rough cross sectional view showing a facsimile machine relative to the embodiments of the present invention;

FIG. 7 is a perspective view showing the facsimile machine relative to the embodiments of the present invention;

FIG. 8 is a enlarged view showing the original pressing means and the contact image sensor of a third embodiment of the present invention;

FIG. 9 is a perspective view showing the original pressing means of a fourth embodiment of the present invention;

FIG. 10 is a enlarged view of the original pressing means of the fourth embodiment of the present invention;

FIG. 11 is a normal cross sectional view of the image reading apparatus relative to the fourth embodiment of the present invention;

FIG. 12 is a normal cross sectional view of the facsimile relative to the fourth embodiment of the present invention;

FIG. 13 is a normal cross sectional view of the image reading apparatus comprising the original pressing means relative to a fifth embodiment of the present invention;

FIG. 14 is an enlarged view of the original pressing means relative to a sixth embodiment of the present invention;

FIG. 15 is a rough cross sectional view showing the image reading apparatus of the prior art; and

FIG. 16 is a side view showing the original pressing means of the prior art.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanied drawings. It is to be understood, however, that the spirit and scope of the present invention are not limited to the size, material, shape, relative arrangement of the components and the like described in the embodiments unless particularly described otherwise.

With reference to FIG. 1 to FIG. 7 , an image reading apparatus and an image forming apparatus relative to the embodiments will be described. Note that, as for the order of descriptions, in the first place, the rough configuration of a facsimile machine as the image forming apparatus will be described and, then, the configuration and the operations of the image reading apparatus will be described.

First Embodiment

First, with reference to FIG. 6 , FIG. 7 , the configuration of the facsimile machine as one example of the image forming apparatus will be described.

In FIG. 6 and FIG. 7 , 1 is an apparatus body and configured by an image reading portion 2 which is the image reading apparatus for reading the image of an original S as a reading object and an image forming portion 10 forming an image on a recording paper P as the sheet of a recording object.

The image reading portion 2 comprises: a top cover 8 having an original mounting stand 8 a capable of mounting a plurality of originals S; a contact image sensor 4 as an image reading means for reading the image information of the original S; and an original pressing means 5 for pressing the original S to the contact image sensor 4 .

Also, the image reading portion 2 feeds the original S mounted on the original mounting stand 8 a one sheet each in order, and has an original conveying portion 3 for conveying the original via the contact image sensor 4 and an upper original guide 6 as well as a lower original guide 7 forming the conveying path of the original S.

An top cover 8 having the original mounting stand 8 a is mounted on the apparatus body 1 in such manner that it can open and close so that the replacement of the cartridge to be described later and the disposal of a paper jam can be easily executed.

Also, a slider 8 b slidable in the width direction orthogonal to the conveying direction of the original S is disposed on the original mounting stand 8 a in such manner that both ends in the width of the original S mounted on the original mounting stand 8 a can be made identical by the slider 8 b.

Also, as shown in FIG. 3 , the contact image sensor 4 is such that, for example, light from a LED array 4 a as a light source passes through a reading window portion 4 d having light permeability and irradiates the image information surface of the original S, while the reflective light reflected from the image information surface is image-formed on a sensor element 4 c by a selfoc lens 4 b (a registered trade mark) after passing the reading window portion 4 d again and reads the image information. For the reading window portion 4 d , though a material such as glass and the like is generally used, its use is not limited to this if there is available any material having light permeability.

Note that the detailed description of the image reading portion 2 as the image reading apparatus applying the present invention will follow later.

The image forming portion 10 comprises: a recording paper mounting portion 23 for mounting a recording paper P; a recording paper feeding portion 12 for feeding the recording paper P one sheet each in order from the recording paper mounting portion 23 ; an image forming means 11 for forming an image on the fed recording paper P; and a laser scanner 13 for irradiating a laser light as the image information on the image forming means 11 .

Also, the image forming portion 10 has: a shared discharge tray 19 for mountably holding the recording paper P discharged after the completion of image forming or the original S discharged after the completion of reading; a recording paper discharge stand 18 for mountably holding the recording paper P discharged U-turn-wise after the completion of image forming; and a conveying guide 17 for guidably holding the recording paper P to be conveyed.

In the recording paper feeding portion 12 , when the feeding commences, the recording paper P compressed to a separating roller 12 b is separated one sheet each by the separating roller 12 b and a separating pad 12 a compressed thereto and, thereafter, conveyed between a photosensitive drum 11 a of the image forming means 11 and a transferring means 11 f with a good timing so that the top end of the image (the toner image) formed on a photosensitive drum 11 a of the image forming means 11 is made identical with the top end of the recording paper P by a conveying roller 12 c and a conveying roller 12 d compressed thereto which rotates slavely.

Note that the recording paper mounting portion 23 is capable of mounting a plurality of recording papers P and the number of recording papers possible to mount for setting is counted approximately as 100 sheets.

Moreover, the size of the recording papers possible to mount for setting is considered to be three kinds of A4 size, a letter size and a regal size. However, the present invention is not limited to the above in the number and the size of the recording papers possible to mount for setting, but it can be suitably arranged as occasion demands.

A cassette portion 20 of the recording papers P is arranged at the base of the apparatus body 1 . The recording papers P mounted on the cassette 20 a are compressed to a separating roller 14 b by the rotation upward of an intermediate plate 20 c by a compressing member 20 b , and are separated one sheet each by a separating pad 14 a (a friction piece separating method) and conveyed along a separating pad guide 14 e and further reversed by a convey roller 14 c , a cover side U-turn guide 14 f arranged on the rear cover and a apparatus side U-turn guide 14 g arranged on the apparatus body side, and finally reach a conveying roller 12 c.

Thereafter, the operations are the same as the above described image forming portion 10 . The selection of the recording paper mounting portion 23 and the cassette sheet feeding portion 20 can be made at random.

In the image forming means 11 , first, on the basis of an image signal, the laser beam which is an image signal is emitted from the laser beam generator of a laser scanner 13 . This laser beam is irradiated at the photosensitive drum 11 a of the image forming means 11 by a polygon mirror 13 b , a lens 13 a and a folded mirror 13 c , and an image is formed on the surface of the photosensitive drum 11 a.

In the image forming means 11 , the photosensitive drum 11 a is assembled into the inside of a frame body together with a charging means 11 b as a processing means acting on the drum, a developing means 11 c and a cleaning means 11 d so that a processing cartridge 11 e is configured. This processing cartridge 11 e is configured in such manner that it is detachable from the apparatus body 1 .

Consequently, at the above described image forming time, the laser beam from the laser scanner 13 is irradiated on the surface of the photosensitive drum 11 a charged uniformly by the charging means 11 b so that a latent image is formed and the latent image is developed into an actual image (a toner image) by toner supplied from a developing means 11 c.

Also, in the image forming means 11 , the transferring means 11 f for transferring the toner image formed on the surface of the photosensitive drum onto the recording paper P is arranged around the peripheral region of the photosensitive drum 11 a , and moreover, a fixing means 24 for fixing the transferred toner image onto the recording paper P is arranged in the recording paper conveying path at the side of the photosensitive drum 11 a . Note that, in FIGS. 6 , 15 , 16 are a pair of discharging rollers.

Consequently, the configuration is such that after the toner image formed on the surface of the photosensitive drum 11 a by the transferring means 11 f is transferred, the recording paper P fed timely to the image forming means 11 from the recording paper mounting portion 23 is conveyed along a conveying guide 17 with the toner image fixed by the fixing means 24 and discharged to the shared discharging tray 19 from the pair of discharging rollers 15 or to a recording paper discharging stand 18 from the pair of discharging rollers 16 via an U-turn path.

Note that, in case where a paper jam is developed while forming an image, the recording paper P remained inside the apparatus can be easily taken out by opening a closing bar of the top cover 8 having the original mounting stand 8 a.

Next, the structure and operations of the image reading portion 2 will be described with reference to the accompanied drawings FIG. 1 to FIG. 5 .

FIG. 1 is a principal perspective view showing a state of coupling between the original pressing means 5 and the upper original guide 6 . FIGS. 2A to 2 D are block diagrams of the original pressing means 5 , and FIG. 2A is an upper view, FIG. 2B a side view, FIG. 2C a front view, and FIG. 2D a enlarged view cut along 2 D— 2 D line of FIG. 2 C. FIG. 3 is a type cross-sectional view of an image reading portion 2 . FIG. 4 , FIG. 5 are a enlarged view of show image reading portion showing the enlarged original pressing means 5 and a contact image sensor 4 .

First, with reference to FIG. 3 , the structure of the image reading portion 2 will be described along the flow of the original S. As shown in FIG. 3 , in the image reading portion 2 , when the original S is mounted on the original mounting stand 8 a (refer to FIG. 6 ), the top end of the original S is interposed between a separating roller 3 a and a pre-compressing arm 3 h compressed thereto.

After the original S is set in this manner and when the conveying of the original S commences, the original S is conveyed to the friction piece 3 b by the separating roller 3 a and the pre-compressing arm 3 h compressed thereto.

And the original S is separated one sheet each and conveyed to the friction piece 3 b by the separating roller 3 a and the friction piece 3 b compressed thereto.

The original S thus separated into one sheet each is conveyed to the contact image sensor 4 by a sheet feeding roller 3 c pressed by a pressing spring 3 i and a compressing sheet feeding roller 3 d and the like, and while being pressed by the original pressing means 5 mentioned later and contacted by the contact image sensor 4 , the original S is successively line-feeded so that the image information thereof is read out.

Thereafter, the original S is discharged to a shared discharging tray 19 (refer to FIG. 7 ) by a sheet discharging roller 3 e pressed by the pressing spring 3 i and a compressing sheet discharging roller 3 f.

During this time, the original S is guided by the upper original guide 6 and a lower original guide 7 and conveyed to the original conveying path.

Note that, on the upper original guide 6 side, there are disposed the pre-compressing arm 3 h , the friction piece 3 b , the sheet feeding roller 3 c , the sheet discharging roller 3 e , the pressing spring 3 i , the original compressing means 5 and the like, while on the side of the lower original guide 7 side, there are disposed the separating roller 3 e , the sheet feeding roller 3 d , the sheet discharging roller 3 f , the contact image sensor 4 and the like.

And the upper original guide 6 side is closable in the arrow mark direction as shown in FIG. 3 against the lower original guide 7 side. Consequently, when a paper jam and the like are developed, the original conveying path is released by opening the upper original guide 6 side and the disposal of the paper jam can be easily executed.

Next, the original pressing means 5 will be described in detail. In FIG. 1 and FIG. 2 , FIG. 3 , the original pressing means 5 is for pressing the original S to the contact image sensor 4 .

This original pressing means 5 is configured by the white sheet 5 a which is a color reference member and an original pressing member 5 b for pressing the original S to the reading surface of the contact image sensor 4 via the white sheet 5 a.

As shown in FIG. 2 , the white sheet 5 a and the original pressing member 5 b are connected by a double-tape. Note that the connecting method for the white sheet 5 a and the original pressing member 5 b is not limited to this, but both of them may be connected by adhesive other than the double-tape (such as acrylic, rubber-based adhesive) or binding material.

Also, as shown in FIG. 1 and FIG. 2 , the white sheet 5 a has a mounting hole 5 a 1 which becomes a mounting portion to the upper guide 6 on its longitudinal both ends (both ends in width direction orthogonal to the original conveying direction). In the present embodiment, the white sheet 5 a has the length in which the portion having the mounting hole 5 a 1 is added to the longitudinal length of the original pressing member 5 b , and the portion having the mounting hole 5 a 1 is bent in the both ends portion of the original pressing member.

This white sheet 5 a is deformable and, concretely for example, formed by material such as polyester film, synthetic paper (the so-called YUPO), polycarbonate sheet, vinyl chloride sheet and the like.

And, on the upper guide 6 , a triangle rib 6 a as a hanging portion for hangingly supporting the mounting hole 5 a 1 of the while sheet 5 a is disposed. In FIG. 1 , the upper original guide 6 is omitted and the triangle rib 6 a alone is shown.

Moreover, on the triangle rib 6 a , a slip-out stopping portion 6 b for stopping the slip-out of the mounting hole 5 a 1 of the white sheet 5 a and a slope 6 c for guiding the mounting hole 5 a 1 of the white sheet 5 a when the original pressing means 5 is mounted on the upper original guide 6 .

Here, clearances t 1 to t 4 formed when the triangle rib 6 a is hangingly supported by the mounting hole 5 a 1 are the clearances disposed so that the original pressing means 5 can move to predetermined locations.

Consequently, the mounting of the original pressing means 5 thus connected as described above to the upper original guide 6 can be easily executed by pushing the mounting hole 5 a 1 of the white sheet 5 a along the slope 6 c of the triangle rib 6 a and by opening outside the longitudinal direction the mounting hole 5 a 1 of the white sheet 5 a slackened inside the longitudinal direction by the pushing and then by inserting the mounting hole 5 a 1 into the triangle rib 6 a of the upper original guide 6 .

As described above, since the original pressing member 5 b is connected to the white sheet 5 a by the double-tape, the mounting can be executed just simply by pushing the deformable white sheet 5 a connected to the original pressing member 5 b into the predetermined location of the upper original guide 6 and by inserting the mounting hole 5 a 1 into the triangle rib 6 a of the upper original guide 6 .

The method for preventing the adhesion (or cohesion) of the image reading portion to the white sheet 5 a in the present invention is shown in FIG. 4 . The original pressing member 5 b has a side 5 b 1 in the bent portion bent up approximately at an angle of 90° in the original conveying direction downstream side, and the upper original guide 6 has a regulating surface 6 d so as to make an acute angle y° with a reading surface 4 a . In the sample of FIG. 4 , the value of y° is 88°.

Since the reading surface 4 a has an angle θ and inclined as shown in FIG. 3 , the original pressing member 5 b in FIG. 4 is configured in such manner that the side 5 b 1 follows a regulating surface 6 d of the upper original guide 6 owing to a gravity, and the original conveying direction downstream side end portion of a pressing surface 5 a 2 for pressing the original S is fixed in the state separated from the reading surface 4 a and makes a clearance x. This clearance x can be adjusted by the value of y.

According to this configuration, a Z portion alone which is the original convey direction upstream side end portion of the pressing surface 5 a 2 becomes the contact portion of the white sheet 5 a and the reading surface 4 a , and in a reading location V portion, a minute clearance can be disposed. For the value of this minute clearance, it is desirable to be set within an image reading possible range of the contact image sensor (for example, within the depth of focus of a reading optical system).

Thus, the reduction in brightness of the pre-scanning time by the adhesion (or cohesion) of the white sheet 5 a to the reading surface 4 a can be prevented and a constant output can be always obtained.

Second Embodiment

Also, as shown in FIG. 5 , by disposing the original pressing compression spring 5 c as a compressing means at the rear side of the original pressing means 5 , the pressing of the original is increased. At this time, by having the original pressing compression spring 5 c run on the upstream side slope 5 b 2 of the original guide portion disposed in the original conveying direction upstream side of the pressing surface 5 a 2 of the original pressing member 5 b , the force in the arrow mark direction is activated even if pressed by the original pressing compression spring 5 c and the above described clearance can be definitely secured.

Third Embodiment

FIG. 8 is a drawing showing the third embodiment of the present invention. In the present embodiment, the upstream side in the original conveying direction of the original pressing member 5 b is floated and, even in this embodiment, the adhesion (or cohesion) in the reading portion can be prevented.

In the same drawing, the original pressing compression spring 5 c is arranged against the original pressing member 5 b as shown in the drawing, and by activating the force shown as f′ in the drawing, the original conveying direction upstream side of the original pressing member 5 b is floated, thereby forming a clearance X.

By the formation of this clearance, the adhesion (or coheshion) in the image reading portion can be prevented.

Note that, in the present embodiment, the configuration is shown in which the original pressing compression spring is used. However, for the method for floating the upstream side, other configuration may be used in which, for example, the dead load alone of the original pressing member is employed similar to the first embodiment. Of course, there is no limit imposed on these methods.

In the above described embodiment, three pieces of the original pressing compression spring 5 c are used longitudinally. Needless to say, however, the present invention does not limit the number of pieces. Although, in the above described embodiment, one sample of the original pressing means 5 is shown, it is needless to mention that the present invention is not limited to this, and the original pressing means 5 using metal for the original pressing member 5 b can be also used.

Note that the original pressing means 5 may be coated with white paint with the coated surface thereof used as a color reference. Moreover, the original pressing means itself may be configured by white material.

Fourth Embodiment

An image reading apparatus and an image forming apparatus relative to the fourth embodiment will be described in detail with reference to the accompanied drawings. Note that, as for the order of descriptions, in the first place, a rough configuration of a facsimile machine will be described, and then, the configuration of the image reading apparatus applying the present invention and the operations thereof will be described.

First, a rough configuration example of a different facsimile machine as the image forming apparatus will be described with reference to FIG. 12 . In FIG. 12 , 101 is an apparatus body and configured by an image reading portion 102 for reading the image of an original S as a reading object and an image recording portion 110 for recording the image on a recording paper P as a recording object.

The above described reading portion 102 has: a top cover 108 having an original mounting stand 108 a capable of mounting a plurality of originals S; an contact image sensor 104 as a reading means for reading image information of the original S; an original pressing means 105 for pressing the original S to the contact image sensor 104 ; an original conveying portion 103 for conveying one sheet each of the original S mounted on the above described original mounting stand 108 a via the above contact image sensor 104 ; and an upper original guide 106 and a lower original guide 107 forming a conveying path of the original S.

The top cover 108 having the above described original mounting stand 108 a is mounted on the apparatus body 101 with capability of closing and opening so that the replacement of an ink recording cartridge 111 e and the disposal of a paper jam can be easily executed. Also, on the above described original mounting stand 108 a , a slider 108 b is disposed which is capable of sliding in the width direction orthogonal to the conveying direction of the original S so that both ends of the original S mounted on the original mounting stand can be made identical by the slider 108 b.

Also, the contact image sensor 104 as the reading means irradiates light on the image information from a LED array as a light source and reads the image information by image-focusing the reflective light reflected on the image information surface on sensor elements by a selfoc lens (a registered trademark).

The above described image recording portion 110 has: a mounting portion 123 for mounting a recorded paper P as a recording object; a recording paper feeding portion 112 for feeding the recording paper P from the recording paper mounting portion 123 one sheet each in order; an image forming portion 111 for record-forming the image on the fed recording paper P; and a recording paper discharging tray 118 for mountably-holding the recording paper P discharged after recording.

Next, referring to FIG. 11 , the configuration of the image reading portion 102 using the original pressing means will be described along with the flow of the original. FIG. 11 is a normal front view of the image reading portion. In the image reading portion 102 , when the original S is mounted on the original mounting stand 108 a , the tip of the original S is interposed between a separating roller 103 a and a pre-compressing arm 103 h compressed thereto. In this manner, after the original is set and when the conveying of the original S starts, the above described original S is conveyed to a friction piece 103 b by the separating roller 103 a and the pre-compressing arm 103 h compressed thereto, and separated one sheet each by the separating roller 103 a and the friction piece 103 b compressed thereto for further feeding. The original thus separated one sheet each is conveyed to the contact image sensor 104 by a sheet feeding roller 103 c pressed by a pressing spring 103 i and a compressed sheet feeding roller 103 d and the like and, while being pressed to the contact image sensor 104 by the original pressing means 105 to be described later, the original S is successively linefeeded so that the image information thereof is read out. Thereafter, the original S is discharged to an original sheet discharging tray 119 (refer to FIG. 12 ) by a sheet discharging roller 103 f compressed to a sheet discharging roller 103 e pressed by a pressing spring 103 i . During this time, the original S is guided by an upper original guide 106 and an lower original guide 7 .

Note that, on the upper original guide 106 side, there are disposed the pre-compressing arm 103 h , the friction piece 103 b , the sheet feeding roller 103 c , the sheet discharging roller 103 e , the pressing spring 103 i , the original pressing means 105 and the like and, on the lower original guide 107 side, there are disposed the separating roller 103 e , the sheet feeding roller 103 d , the sheet discharging roller 103 f , the contact image sensor 104 and the like. The upper original guide 106 side is capable of closing and opening against the lower original guide 107 side in the arrow mark direction A. Consequently, when a paper jam is developed, the original conveying path is released by opening the upper original guide 106 , thereby the disposal of the paper jam can be easily executed.

Next, the above described original pressing means 105 will be described in detail. FIG. 9 is a perspective view showing the state of fixing the original pressing means and the upper original guide, and FIG. 10 is a main cross-sectional enlarged view of the original pressing member and its surrounding region as seen from the arrow mark B in FIG. 9 . In FIG. 9 and FIG. 10 , FIG. 11 , 105 is the original pressing means and it is for pressing the original S to the contact image sensor 104 . This original pressing means 105 is configured by a white sheet 105 a which is a color reference member and the original pressing member 105 b for pressing the original S on the reading surface of the contact image sensor 104 via the white sheet 105 a.

As shown in FIG. 10 , the above described white sheet 105 a and the original pressing member 105 b are connected by a double tape. Note that the method for connecting the above described sheet 105 a and the original pressing member 105 b is not limited to this, but both of them may be connected by adhesive other than the double-tape (such as acrylic, rubber-based adhesives) or bonding material.

Also, as shown in FIG. 9 , the white sheet 105 a has a mounting hole 105 a 1 which becomes a mounting portion to the upper original guide 106 on its longitudinal both ends (both ends in the width direction orthogonal to the original conveying direction) in the original conveying direction upstream side. This white sheet 105 a is deformable and definitely for example, formed by material such as polyester film, synthetic paper (the so-called YUPO), polycarbonate sheet, vinyl chloride sheet and the like.

And, on the upper original guide 106 , a triangle rib 106 a as a hanging portion for hangingly support a mounting hole 105 a 1 of the above described white sheet 105 a is disposed.

Moreover, on the triangle rib 106 a , a slip-out stopping portion 106 b for stopping the slip-out of the mounting hole 105 a 1 of the white sheet 105 a and a slope 106 c for guiding the mounting hole 105 a 1 of the white sheet 105 a when the original pressing means 105 is mounted on the upper original guide 106 . Here, clearances t 1 to t 4 are the clearances disposed so that the original pressing means can move to predetermined locations.

Moreover, the original pressing member 105 b has a projecting portion 105 b 3 which becomes the mounting portion to the upper original guide 106 in the original conveying direction downstream side at longitudinal both ends. And, on the upper original guide 106 , a mounting hole 106 d for hangingly support the projecting portion 105 b 3 of the above described pressing member 105 b is disposed. Here, t 1 ′ to t 4 ′ are clearances in which the original pressing member can move to predetermined locations.

Consequently, the mounting of the original pressing means 105 combined as above to the upper original guide 106 can be easily executed by inserting the projecting portion 105 b 3 of the original pressing member 105 b into the mounting hole 106 d of the upper original guide 106 , and by pushing the mounting hole 105 a of the white sheet 105 a along the slope 106 c of the triangle rib 106 a , and then by inserting the mounting hole 105 a of the white sheet 105 a into the triangle rib 106 a.

In FIG. 10 , the method for preventing the adhesion (or cohesion) of the white sheet to the reading portion in the present invention is shown. The original pressing member 105 b opposing to the reading location 104 b (an alternate long and short dash line) of the contact image sensor in the image reading portion 102 is configured such that a concave portion 105 b 4 recessed in the shape of a concave is disposed which is pressed down by dead load alone of the original pressing member 105 b . By so doing, the dead load of the original pressing member 105 b is not applied to the reading location 104 a . Consequently, since the white sheet 105 a is not given a pressure at the reading location 104 b , the deterioration of brightness at the time of the pre-scanning owing to the adhesion to the reading surface 104 a is prevented so that a constant output can be always obtained. This time, the original pressing member 105 b uses a sheet steel and a clearance between the concave portion 105 b 4 and the reading surface 104 a is set at 0.7 mm by a longitudinal bead drawing. Needless to mention, for the original pressing member 105 b , integral molding components using resin members may be used.

Also, as the fifth embodiment, as shown in FIG. 13 , the embodiment is configured in such manner that, by pressing the original pressing member 105 b to the reading surface 104 a by using the original pressing compression spring 105 c , the original can be adhered to the reading surface 104 a more reliably than by dead load of the original pressing member 105 b . At this time also, the white sheet 105 a does not stick to the reading surface 104 a in the reading location 104 b and, therefore, the deterioration of brightness at the time of the pre-scanning is prevented so that a constant output can be always obtained. This time, the spring is used longitudinally at three places. Needless to mention, however, the present invention does not depend upon the number of springs used.

Moreover, as the sixth embodiment, as shown in FIG. 14 , the embodiment may be configured in such manner that the original pressing member 105 b using the sheet steel is completely recessed from the reading location 104 b by being bent in a rectangular shape around the peripheral region of the reading location 104 b.

In the above described embodiment, one sample of the original pressing means is shown. Needless to mention, however, the present invention is not limited to this, but can be applied to the original pressing means using metal.